1) Field of the Disclosure
The disclosure relates generally to methods for bonding of structures, and more particularly, to methods for promoting adhesion and bonding of composite and metal structures, and the bonded structures produced thereby, such as for use in aircraft, spacecraft, and other vehicles and structures. Further, this disclosure relates generally to barrier coatings and methods for application of barrier coatings, and more particularly, to high temperature adhesion barrier coatings and methods for application of such high temperature adhesion barrier coatings.
2) Description of Related Art
Composite and metal structures or component parts are used in a wide variety of applications, including in the manufacture of aircraft, spacecraft, rotorcraft, watercraft, automobiles, trucks, and other vehicles and structures. In particular, in aircraft construction, structures or component parts, such as composite structures or component parts, are used in increasing quantities to form the fuselage, wings, tail section, and other component parts of the aircraft. Such large-sized structural aircraft components may be manufactured by bonding together composites to composites, composites to metals, and metals to metals.
Known methods and systems for bonding composite and metal component parts together, such as aircraft component parts, typically involve using fastener devices, such as bolts, screws, pins, or other fastener devices to secure the component parts together. However, using such known fastener devices can add to the overall weight of the aircraft, which can, in turn, increase fuel costs. Further, using such known fastener devices can take time and labor to install and can require procurement and storage of the fastener devices, which can, in turn, increase installation, labor, and manufacturing costs.
In addition, known methods and systems for bonding composite and metal component parts together, such as aircraft component parts, typically also involve using film adhesives to join or bond two composite materials together, two metal materials together, or a composite material to a metal material. In order to form the large-sized structural component, the components are firstly positioned and aligned with respect to one another on a suitable supporting structure, in accordance with previously known methods. The adhesive films are typically applied in advance between the components which are to be adhesively bonded to one another. To improve structural bonding, known methods exist for modifying the surface of the composite or metal structure or part prior to applying the adhesive. Known surface modification methods may require the roughening of the composite or metal surface via sanding or grit blasting. Such known procedures can create some active oxide functional groups on the surface. However, it is believed that no known methods or systems exist for durable surface modification for improved structural bonding and for identifying functional groups which have an affinity to enhance durable and sustainable structural bonding and thereby improve secondary bonding forces (Van der Waals forces) and which can, in turn, increase the durable, long-term life of a composite bonded joint.
In addition, high temperature barrier coatings for composite and metal structures are known. Such known high temperature barrier coatings may comprise primers for structures. However, such primers may form thick films, such as thick adhesion promoters or corrosion prevention layers, which may be more sensitive to the thickness of the deposited film and may be too thick, and which may, in turn, affect mechanical performance of the structure. Moreover, such primers may form films that may be too thin, and which may, in turn, cause the film to be ineffective.
Attempts at durable high temperature surface modification for improved high temperature structural adhesion barrier coatings under hostile operating environments have been made. For example, typical known processes require the roughening of the composite or metallic surface via sanding or grit blasting to mitigate possible exfoliation. However, such processes may create some active oxide on the surface but not to the extent that the oxide groups themselves affect the thermal oxidative stability (TOS) of the structural members.
Moreover, attempts have been made to produce high temperature barrier coatings that can provide adhesion promotion for structural bonding and minimize thermal oxidative degradation. However, such attempts may impact structure life, damage tolerance, and durability, and may not sustain the structure under high temperature, hostile operating environments.
Accordingly, there is a need in the art for methods and systems for promoting adhesion and bonding of composite and metal structures that provide advantages over known methods and systems. Moreover, there is a need in the art for high temperature adhesion barrier coatings and methods that provide advantages over known coatings and methods.